Hydrant backflow restriction system

Abstract

A hydrant backflow prevention system comprises a backflow prevention valve, operably coupleable to a hydrant to restrict passage of materials through the hydrant into a water supply feeding the hydrant. The backflow prevention valve is installable fluidly inline with the water supply at a location below which an upper dry barrel of the hydrant is coupled to a water delivery system. The backflow restriction valve is operable to substantially restrict backflow into the water supply when in a closed position, and allow flow of water through the hydrant when in the open position.

1. A hydrant backflow prevention system, comprising:
 a backflow prevention valve operably coupleable to a hydrant to restrict passage of materials through the hydrant into a water supply feeding the hydrant, the backflow prevention valve being installable fluidly inline with the water supply at a location upstream of an upper dry barrel of the hydrant, the backflow restriction valve being operable to: 
 i) substantially restrict backflow into the water supply when in a closed position, and 
 ii) allow flow of water through the hydrant when in the open position, wherein the backflow prevention valve includes: 
 a venturi housing including a seat formed or attached therein; and 
 a riser positioned on the seat in a closed configuration, and being operable to be suspended away from the seat in response to positive fluid flow through the hydrant. 
 
     
     
       2. The system of  claim 1 , wherein the location is at or below ground level. 
     
     
       3. The system of  claim 1 , wherein the backflow prevention valve allows flow of water through the hydrant while adding a backflow valve head loss of less than about 3 psi at 750 gpm. 
     
     
       4. The system of  claim 3 , wherein the backflow valve head loss is between about 0.5 psi and about 3 psi. 
     
     
       5. The system of  claim 3 , wherein the backflow valve head loss is less than about 0.5 psi. 
     
     
       6. The system of  claim 1 , wherein the riser is operable to be suspended away from the seat a distance sufficient to maintain the riser substantially away from non-laminar flow of the water as the water flows positively through the venturi housing and around the riser. 
     
     
       7. The system of  claim 1 , wherein the riser is configured to substantially seal against the seat when water is not flowing through the hydrant. 
     
     
       8. The system of  claim 1 , wherein the venturi housing is installable within an existing conduit of the water delivery system. 
     
     
       9. A hydrant backflow prevention system, comprising a backflow prevention valve, operably coupleable to a hydrant to restrict passage of materials through the hydrant into a water supply feeding the hydrant, the backflow prevention valve, including:
 i) a venturi housing including a seat formed or attached therein; and 
 ii) a riser positioned on the seat and operable to be suspended away from the seat in response to positive fluid flow through the hydrant, said riser being suspended away from the seat at a distance sufficient to maintain the riser substantially away from turbulent flow of the water as water flows positively through the venturi housing and around the riser. 
 
     
     
       10. The system of  claim 9 , wherein the backflow prevention valve is installable at a location below an upper dry barrel of the hydrant. 
     
     
       11. The system of  claim 10 , wherein the location is at or below ground level. 
     
     
       12. The system of  claim 9 , wherein the backflow prevention valve allows flow of water through the hydrant while adding to an overall head loss of the hydrant a backflow valve head loss of less than about 3 psi at 750 gpm. 
     
     
       13. The system of  claim 12 , wherein the backflow valve head loss is between about 0.5 psi to about 3 psi. 
     
     
       14. The system of  claim 12 , wherein the backflow valve head loss is less than about 0.5 psi. 
     
     
       15. The system of  claim 9 , wherein the riser is configured to substantially seal against the seat when water is not flowing through the hydrant. 
     
     
       16. The system of  9 , wherein the venturi housing is installable within an existing conduit of the water delivery system. 
     
     
       17. A method of protecting a water supply from introduction of contaminants into the water supply through a hydrant, comprising:
 a) removing an upper dry barrel of a hydrant; 
 b) installing a backflow prevention valve fluidly inline with a water supply feeding the hydrant at a location below the upper dry barrel, the backflow prevention valve being operable to:
 i) substantially restrict backflow into the water supply when in a closed position, and 
 ii) allow flow of water through the hydrant when in the open position; and 
 
 c) reinstalling or replacing the upper barrel of the hydrant, wherein the backflow prevention valve includes: 
 a venturi housing including a seat formed or attached therein; and 
 a riser positioned on the seat in a closed configuration, and being operable to be suspended away from the seat in response to positive fluid flow through the hydrant. 
 
     
     
       18. The method of  claim 17 , wherein the location is at or below ground level. 
     
     
       19. The method of  claim 17 , wherein the backflow prevention valve allows flow of water through the hydrant while adding to an overall head loss of the hydrant a backflow valve head loss of less than about 3 psi at 750 gpm. 
     
     
       20. The method of  claim 19 , wherein the backflow valve head loss is between about 0.5 psi to about 3 psi. 
     
     
       21. The method of  claim 19 , wherein the backflow valve head loss is less than about 0.5 psi. 
     
     
       22. The method of  claim 17 , wherein the riser is operable to be suspended away from the seat a distance sufficient to maintain the riser substantially away from non-laminar flow of the water as the water flows positively through the venturi housing and around the riser. 
     
     
       23. The method of  claim 17 , wherein the riser is configured to substantially seal against the seat when water is not flowing through the hydrant. 
     
     
       24. The method of  claim 17 , wherein the venturi housing is installable within an existing conduit of the water delivery system.